Project Summary Each year more than 68,000 Americans are diagnosed with melanoma, the deadliest form of skin cancer that can easily progress to metastasis. Although the discovery of cancer specific metabolic dependency reveals novel targets suitable for mono- or combinatorial therapy, the heterogeneous nature of melanoma allows selective outgrowth of resistant clones that can be further invasive and metastatic. Increasing our understanding of the mechanisms defining melanoma heterogeneity and driving metastasis will help identify biomarkers that can be used to predict them, and targetable signaling pathways that can be used to prevent them. The main goal of this proposal is to investigate how do mitochondria cooperate with other cellular factors to modulate metastasis and how to target mitochondrial metabolism or components for melanoma modality. Firstly, although we have shown that PGC1? defines melanoma mitochondrial dependency, targeting approach for this vulnerability is lacking. The purpose of Aim 1 is to further dissect the molecular pathways downstream of PGC1? in the regulation of melanoma metabolism, with special emphasis on the roles of ERR? and its potential to translate into therapy. Secondly, PGC1?-mediated mitochondrial heterogeneity correlates with melanoma metastatic capability and responsiveness to targeted therapy. In Aim 2, we will experimentally address the mitochondrial proteomic heterogeneity and the specific roles of selected mitochondrial components in regulating metastasis and response to BRAFV600E inhibition. Lastly, we have developed an in vivo metastasis model suitable for large-scale screening for metastasis regulators. In Aim 3, we will perform loss- and gain-of-function CRISPR screens to identify novel genes regulating melanoma metastasis. I also propose an extensive training program that will support my transition to independence. The research environment provided by Dana-Farber Cancer Institute and Harvard Medical School is outstanding, and offers exceptional opportunities for scientific discussion, collaboration and career development. My training will also involve mentoring students, attending and presenting my work at meetings to become an active member of the cancer and metabolism communities. Taken together, the proposed studies and training in career development will ensure I achieve my goal of establishing a successful, independently funded lab at a major university.